Feed roller mechanism

ABSTRACT

An apparatus for transporting a sheet comprising: a first roller; a second roller; and an assembly for mounting the second roller for movement between a position spaced from the first roller and a position engaging the first roller for transporting a sheet; wherein the second roller has first and second ends, and wherein the assembly includes independently spring loaded link assemblies respectively on the first and second ends of the second roller that ensure that the second roller will always close down on both sides of the first roller with uniform pressure on both sides.

FIELD OF THE INVENTION

[0001] This invention relates in general to laser imagers and moreparticularly to an improved feed roller mechanism forming part of thefilm transport system.

BACKGROUND OF THE INVENTION

[0002] Laser imagers are widely used in the medical imaging field toproduce visual representations on film of digital medical images. Laserimagers typically include a film supply and transport system, a filmexposure system, and a film processing system. The film supply andtransport system includes a supply of unexposed film stacked in acartridge or magazine, a mechanism for removing individual sheets offilm and delivering each sheet to a film transport system. The filmtransport system then transports the film through the film exposure andfilm processing systems to an output tray for access by a user.

[0003] U.S. Pat. No. 6,260,842, issued Jul. 17, 2001, inventors Nelsonet al. disclose a film supply system for use with a resealable filmcartridge containing a stack of unexposed film. The film supply systemincludes a mechanism for unsealing the cartridge and a mechanism forseparating and delivering individual film sheets to the film transportsystem. As disclosed, the top film is gripped by a suction cupmechanism, the film is bent and the film is separated from the nextadjacent film in the stack and delivered to a feed roller pair.Initially, the film contacts the lower drive roller, the upper idlerroller being held out of contact with the lower roller. Then, therollers are driven closed to secure the film. The rollers are now drivento transport the film away from the film supply system.

[0004] Although successful for its intended purposes, the disclosed feedroller mechanism evidenced certain features that needed improvement.These include the following:

[0005] 1. The idler roller would not clamp evenly across the driveroller.

[0006] 2. The motor was under load while the idler roller was in theopen position, making it susceptible to closing when the motor was notenergized.

[0007] 3. Link mechanisms in the front of the mechanism made itdifficult to clear films in the assembly.

[0008] 4. The stack height of the mechanism was to high for the synergyapplication.

SUMMARY OF THE INVENTION

[0009] According to the present invention, there is provided a solutionto these problems.

[0010] According to a feature of the present invention, there isprovided an apparatus for transporting a sheet comprising: a firstroller; a second roller; and an assembly for mounting said second rollerfor movement between a position spaced from said first roller and aposition engaging said first roller for transporting a sheet; whereinsaid second roller has first and second ends, and wherein said assemblyincludes independently spring loaded link assemblies respectively onsaid first and second ends of said second roller that ensure that saidsecond roller will always close down on both sides of said first rollerwith uniform pressure on both sides.

ADVANTAGEOUS EFFECT OF THE INVENTION

[0011] The invention has the following advantages.

[0012] 1. Independent Spring Loaded Links

[0013] The feed roller mechanism utilizes independently spring loadedlinks on each end of the idler roller. This ensures that the idlerroller will always close down on both sides of the drive roller withuniform pressure on each side. This prevents possible film skew duringfilm feed due to a possible roller gap on one side of the mating pair ofrollers that can occur in a rigid idler roller mechanism.

[0014] 2. No load on Motor in Open and Closed positions

[0015] Traditional open/close feed roller designs utilize torsionsprings with the highest spring load in the max open roller position.The Synergy feed roller mechanism utilizes compression springs that onlyactuate, with a resulting motor load, in the roller close position. Themotor stops in the roller closed position when the idler gear and rockerarm is in a toggle position which is also a no-load condition on themotor. This means that the open and closed feed roller positions will noslip out of position due to motor loading conditions when the motor ispowered down or idled.

[0016] 3. Mechanism is above the Film Plane—Easy Jam Clearance

[0017] The mechanism for the feed rollers that resides in the film areais all above the film feed path. This enables a clear, unobstructedremoval of any film that has jammed in the assembly.

[0018] 4. Low Profile Design

[0019] The feed roller mechanism is a very low profile design whichfacilitates the stacking of multiple film feed assemblies without amajor impact on the overall height of the imager. Multiple feedmagazines allow multiple film sizes to be on-line and ready to feed filminto the imager. In the case where multiple stacked film feed magazines.Every inch saved in the height of the feed roller assembly saves 3inches on the overall height of the imager.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a perspective view of an embodiment of the presentinvention.

[0021]FIGS. 2 and 3 are perspective views of portions of the inventionshown in FIG. 1.

[0022]FIGS. 4-7 are side elevational views useful in describing theoperation of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0023] Referring now to the Figures, there will be disclosed anembodiment of the present invention. As shown in FIG. 1, the feed rollermechanism includes of two drive rollers (3,11) and an idler roller (5)that opens and closes onto to the fixed drive roller (3). The two driverollers (3,11) are housed in the front mount (6) and the rear mount (1)along with a drive shaft (2). Mounted to the drive shaft (2) are twodrive gears (8). The drive gears (8) engage two idler gears (9) thathouse the mechanism for opening and closing the idler roller (5). Theidler gears (9), located at each end of the idler roller (5), aremounted to the pickup frame at weldment (4) and weldment (7). A filmposition sensor (10) is mounted at position in between the two driverollers (10). Spaced guides (31 and 32) are located along a sheettransport path between drive rollers (3 and 11) for guiding a sheetdriven along the path by drive rollers (3 and 11).

[0024]FIG. 2 shows a detail view of the idler roller (5) mountingassembly. This mount assembly is on each end of the idler roller (5)providing an independent spring loaded mounting scheme. The idler gear(9) is pinned to the pickup frame using the idler pin (14) and is freeto turn about this pin (14). A flag (12) also rotates about the idlerpin (14) but is rotationally locked to the idler gear (9). This flag(12) is used to sense the position of the idler gear (9), and resultingidler roller (5) position, using the roller position sensor (21).

[0025] The rocker pin (19) pins the rocker (20) to the idler gear (9),the rocker (20) is free to turn about this pin. The rocker 20 isattached to the drive ring (16) with a shoulder screw (17) (see FIG. 4).The body of the shoulder screw (17) is free to slide along the insidediameter of the rocker (20), while its end is screwed into the drivering (16). This allows the drive ring (16) and rocker (20) to moverelative to each other along the axis of the shoulder screw (17). Theroller spring (18), holds the drive ring (16) and rocker (20) as farapart as possible until the head of the shoulder screw (17) bottoms outon a ledge inside the rocker (20).

[0026] Inserted into the drive ring (16) is the link (15). The end ofthe shaft of the idler roller (5) inserts into a flanged bearing housedin the link (15) and is captivated by an e-ring. The link (15) is pinnedto the pickup frame (4,7) by shaft (13) and rotates the idler roller (5)open and closed relative to the drive roller (3).

[0027]FIG. 3 shows the stepper motor (22) with a motor pulley (29)mounted to its shaft (31). Wrapped around this pulley is a toothed belt(27) that wraps around 2 drive pulleys (28) that are keyed to the endsof the two drive rollers (3,11). The belt (27) is tensioned using afixed idler pulley (26). The two drive rollers (3,11) are driven by thestepper motor (22) with a 50 tooth to 16 tooth ratio. The dc rollermotor (23) is geared to the drive shaft (2) using a pair of drive gears(24,25). This dc roller motor actuates the opening and closing of theidler roller (5) by transmitting torque through the drive shaft (2) intothe drive gears (8) and into the meshed idler gears (9).

[0028] Referring now to FIGS. 4-7, the operation of the presentinvention will be described. FIG. 4 shows the maximum open position ofthe Idler roller (5) relative to the drive roller (3). At this position,the rocker pin (19), which is rigidly mounted to the idler gear (9), hasrotated to position of 190 degrees from horizontal. The idler gear (9)always rotates counterclockwise. The position is located by one edge ofthe flag (12) that engages the roller position sensor (21). As therocker pin (19) rotates, it moves the rocker (20), shoulder screw (17),and drive ring (16) with it. The roller spring (18), holds the drivering (16) and rocker (20) as far apart as possible until the head of theshoulder screw (17) bottoms out on a ledge inside the rocker (20). Thedrive ring (16) is pivotally mounted to one end of the link (15) whichrotates the link (15) counterclockwise until it reaches this top deadcenter position. The idler roller (5), which is mounted into a ballbearing that inserts into the link (15), travels with the rotating link(5).

[0029] In FIG. 5, the idler gear (9) has rotated to the First ContactPosition where the idler roller (5) first makes contact with the driveroller (3). In this position, the rocker pin (19) can no longer rotatecounterclockwise unless the distance between the rocker pin (19) and theidler roller (5) axis is shortened. The mechanism that allows thisdistance to shorten is the axial motion between the shoulder screw (17)and the rocker (20). At this point, a torque load just begins to developon the idler gear (9), prior to this point, the idler was in a no-loadcondition.

[0030] In FIG. 6, the idler gear (9) has rotated to the toggle positionwhere the distance between the rocker pin (19) and the idler roller (5)axis is at its minimum. The shoulder screw (17) has slid axially insidethe rocker (20) by a distance equal to the Spring Compression variableshow in FIG. 6. At this position the spring force is at its maximum andtransmits a force along the shoulder screw (17) axis that has acomponent of force that acts to clamp the idler roller (5) and driveroller (3) together. The torque load on the idler gear (9) in thistoggle position is zero, the torque load on the idler gear (9) reachedits maximum between the first contact position and the toggle position.

[0031]FIG. 7 shows the last contact position where the idler roller (5)is just about to lift off the drive roller (3). Here the roller spring(18) is free to expand until the Spring Compression=0 when the head ofthe shoulder screw (17) once again bottoms out on a ledge inside therocker (20). At this point there is no longer any torque load on theidler gear (9). From this position, the idler gear continues to rotatecounterclockwise which opens the idler roller until it returns to themaximum open position in FIG. 4.

[0032] The invention has been described in detail with particularreference to certain preferred embodiments thereof, but it will beunderstood that variations and modifications can be effected within thespirit and scope of the invention.

Parts List

[0033]1 rear mount

[0034]2 drive shaft

[0035]3 fixed drive roller

[0036]4 weldment

[0037]5 idler roller

[0038]6 front mount

[0039]7 weldment

[0040]8 drive gears

[0041]9 idler rollers

[0042]10 film position sensor

[0043]11 drive roller

[0044]12 flag

[0045]13 shaft

[0046]14 idler pin

[0047]15 link

[0048]16 drive ring

[0049]17 shoulder screw

[0050]18 roller spring

[0051]19 rocker pin

[0052]20 rocker

[0053]22 stepper motor

[0054]23 dc roller motor

[0055]24,25 drive gears

[0056]26 fixed idler pulley

[0057]27 toothed belt

[0058]28 drive pulleys

[0059]29 motor pulley

[0060]31 drive roller shaft

[0061]32,33 guides

What is claimed is:
 1. An apparatus for transporting a sheet comprising:a first roller; a second roller; and an assembly for mounting saidsecond roller for movement between a position spaced from said firstroller and a position engaging said first roller for transporting asheet; wherein said second roller has first and second ends, and whereinsaid assembly includes independently spring loaded link assembliesrespectively on said first and second ends of said second roller thatensure that said second roller will always close down on both sides ofsaid first roller with uniform pressure on both sides.
 2. The apparatusof claim 1 wherein said first roller is a drive roller and second rolleris an idler roller and including a first drive drivingly coupled to saidfirst roller.
 3. The apparatus of claim 2 including a third rollerspaced from said first roller and drivingly coupled to said first drive.4. The apparatus of claim 3 further including spaced guides locatedalong a sheet transport path between said first and third rollers forguiding a sheet driven along said path by said first and third rollersdriven by said first drive.
 5. The apparatus of claim 1 wherein eachsaid link assembly includes a rotatably mounted idler gear, a hollowrocker pivotally mounted at one end by said idler gear, a hollow drivering, a shoulder screw slidably mounted in said rocker and said drivering attaching said rocker to said drive ring, a roller spring which iscoiled about said rocker and said drive ring and which biases saidrocker and said drive ring apart and a link coupled between said drivering and an end of said second roller.
 6. The apparatus of claim 5including a second drive drivingly coupled to said idler gears of saidlink assemblies wherein rotation of said idler gears by said seconddrive causes said rocker and drive ring and said links to move saidsecond roller into engagement with said first roller, and wherein saidrocker and drive ring slide toward each other and compress said springwhen said first and second rollers are fully engaged, thereby clampingsaid first and second rollers together with said clamping force beingindependent on each end.